Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.
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blister; but there was neither felt nor seen any effect until the similar application of a plate of zinc over the other blister and metallic contact was made between them; when, at each con- tact, there was a heavy, dull sensation of burning. This sensa- tion, he says, sensibly increased from half minute to half minute. But what was most surprising to all present was, the appearance of the now flowing secretion from the blisters; it was not transparent, nor was it bland, as before, but in the course of a very short time, it had become reddish, producing evidence of irritation of the skin wherever it flowed over, leaving there red- dish stripes. No angry wound could produce such acrid liquid and quick-made excoriations. The gentleman who aided in these trials repeated the effects by reversing the arrangement of the silver to the left shoulder. In four minutes, violent inflamma- tion set in, with increased local redness, together with the exco- riations of purple and red stripes, produced down the back by the moisture that flowed from under the metal plates that were thus on the raw surfaces. When the experiment was ended, says Humboldt, notwithstanding all the care taken to gently wash away the flowing moisture as well as could be, still did his back appear like a whipped criminal. This very remarkable experiment, for testing the physiological action of that method of using galvanism, was given by Baron Humboldt, the Nestor of natural science, early in the year 1790, and even before the dis- covery of tho voltaic pile, but after the discovery of the electro- muscular contractions by Galvani, through the twitchings of dead frogs from metallic contact, (see page 72;) a phenomenon, which it is well known led Galvani to suppose that the electric source, was no other than that which was native in the muscles and flesh, and that the nerves were only the conductors of the positive, or plus electricity that was accumulated in the deep parts; they only leading it to the negative or minus electricity which was on the surface. But Humboldt offered two explana- tions of this, also, that were satisfactory. The electro-physiological phenomenon of " closing and opening convulsions" has always received the greatest attention, and many ideas have been advanced by philosophers to account 18